Carboxyalkyl ethers of carbohydrate gums



Patented July 26, 1949 CARBOXYALKYL ETHERS F CARBO- HYDRATE GUMS Owen A. Moe, Minneapolis, Minn, assignor to General Mills, Inc., a corporation of Delaware No Drawing.

4 Claims. 1

The present invention relates to carboxyalkyl ethers of carbohydrate gums and to me h of producing the same.

Carbohydrate gums such as locust bean gum are frequently used in aqueous solution. In general, they are extremely dificult to dissolve, requiring long periods of soaking before they can be thoroughly dispersed. This is a particular disadvantage where an aqueous sol of such a gum is desired on short notice. vIn addition, such gums frequently do not disperse completely, and sols of commercially available gums are usually turbid and contain suspended solid particles. Moreover, such sols are usually fairly viscous and accordingly incapable of filtration for removal of the suspended solid.

It has now been discovered that carboxyalkyl ethers, and especially alkali metal salts of the carboxyalkyl ethers of these gums are readily dispersible and form sols of excellent clarity, as compared to untreated gum. The carboxyalkyl ethers of galactomannan gums and glucomannan gums, those containing galactose and mannose units and glucose and mannose units respectively in the gum structure, produce sols of a viscosity comparable to that of the untreated gum. Typical of the galactomannan gums are guar, locust bean, honey locust, flame tree, and the like. Typical of the glucomannans is iles mannan, and the like. In some instances the viscosity of the treated gum may be increased somewhat. It has been noted moreover, that the carboxyalkyl ethers of such gums form gels on addition of a dilute solution of metal salts such as ferrous sulfate. These gels are very firm and can be transferred from one container to another without wetting the surface.

It is therefore a primary object of the present invention to provide novelcarboxyalkyl ethers of carbohydrate gums. It is a further object of the present invention to provide alkali metal salts of carboxyalkyl ethers of carbohydrate gums, said compounds being capable of ready dispersibility in aqueous media and formation of relatively clear sols. It is a further object of the present invention to provide carboxyalkyl ethers of galactomannan and glucomannan type gums which are capable of forming gels from aqueous sol by means of solutions of metal salts such as ferrous sulfate. present invention to provide a process for making such products.

The carboxyalkyl ethers may be formed by treating the gum with a cold aqueous solution of an alkali such as sodium hydroxide and then It is another object of the Application August 25, 1945, Serial No. 612,717

treating the alkali gum with a halo fatty acid or halo fatty acid salt. In general, the treatment of the gum with the cold solution of alkali serves to disperse the gum without the occurrence of lumping. It is also possible to disperse the gum in aqueous alkali at a more elevated temperature by a more efficient stirring means. After dispersion of the gum in the aqueous alkali, the mixture is heated to an elevated temperature such as 90 C. and the reaction mixture will then frequently become semi-solid. This mass is then cooled and broken up into fine particles and treated with the etherifying agent, usually in the form of a halo fatty acid or salt thereof. This reaction mixture is then heated to a temperature of -85 C. for an appreciable period of time, 1 or 2 hours, with eflicient mixing. The reaction mixture is then cooled and diluted with water and made acidic to phenolphthalein. The reaction product may then be precipitated by the addition of a water miscible organic solvent such as methanol, acetone, and the like, and may be washed with a solvent of appropriate concentration for further removal of impurities and then dried and ground.

Any of the galactomannan and glucomannan carbohydrate gums may be treated according to the present invention. Numerous examples of such gums have been mentioned herein and other examples will be apparent to those skilled in the art. Other alkalies such as potassium hydroxide, may be used in place of the sodium hydroxide. In the examples given hereinafter chloracetic acid and its salts are preferred as the etherifying agent in view of the ready availability of this material. Other etherifying agents such as chloropropionate, chlorobutyrate, or other halo fatty acids or salts thereof may be used in place of the chloracetate if desired. Instead of using the gum in a pure isolated form it is also possible to use impure forms of the gum, such as those obtained by merely grinding to a powder the entire seed or other form in which the gum occurs naturally. The carboxyalkyl ethers of the impure forms of gum display the same ready dispersibility and also display remarkable clarity considering the relatively impure nature of the starting material. They will not, in general, however, produce as clear sols as will the ethers of the purified gums.

The following examples will serve to illustrate the invention.

, Example 1 This example demonstrates the preparation of a carboxymethyl derivative of a gum which yields 220 parts of sodium hydroxide solution sodium hydroxide in parts of water) was,

added with efficient mixing. The resulting reaction mixture was heatedin a water ba h to, 80-85 C. for a period of 90 minutes witheffic gent mixing. After cooling, the reactio'n'mixture was diluted with 200 cc. of water and made acidic to phenolphthalein by addition of dilute acetic acid. The reaction product was precipitated by the addition of methanol. The precipitated product thus obtained was Washed with methanol, dried L and groundto a powder. The sodium car-boxy methyl ether of locust bean gum thus prepared was readily dispersible in water to form 1% sols otremarkable clarity and stability and of a vis-' cosity comparable to or higher than than that of the gum itself. A 3% sol of verygeod clarity and high viscositywas very readily obtained. These sols formed gels which were when a solution or a metallic sal-t such as ferrous sulfate wasadded. The gels may be prepared in the following manner: Three to'five parts of a 10% terrous sulfate solution are added to 10 parts of a 3% carboxymethyl gum ethersol with efficient mixing. The gel formation takes place rapidly as the sol is stirred. It is, of course, apparent that the concentrationofthe ferrous sulfate and gum. derivative sols maybe varied over a wide range.

Exa e 2 Th s examrle dem nstrates th are ara n of a bQXymdhy t e f mannpsa actan u wh h, t me. merci ess and. sal ct se n hydrol sis. Fw Par s. f are ene were disrz fsedin;

cgq edtqq Q- lf ie iesultisaallsa i samm l shram 1 a wa er-h th t 89$ Them x ure ceded to mamtemne .t -e za a s ne y pcwaere t h ar ce i d 5. d n wi h Qpling; Aft r the, ad. tion. o chlora et acid. a coma e a, the; ead a mix.-

wash atsd, i a W t rbat w h m xin er. a tie f Q=min1 tes at ,0? 0-, eac ion mi. .1116. as t en. d u ed: t v c of; ater and ne t lize w th. il ta ac d-r he. reac ion Prod c wa pr c ate it a dit on. i methanql nd: e. o e produc wasw lifisi u n he su l. m nn rh s. so um. arbcrymethyl; gum ether. yielded viscous 2L-.-4-.% sQls' in wa er a d ayed o d. lar ty a d tab lity,- lhls, e ativ d s erse a at surpr se llsl ra d a e nd s a eouss ssdi n ay a, gelformation; uponthe. addition.- ofadilute ferm s ulf te sol ti nsel. m t n ak s p ace. r pidlr w th tir in a terthead it cn o he. r ls u iete lu n- Example-.3

This example demonstrates tha preparation of a sodium carboxymethyl gum etherjstarting with a ain. ou l eni nartscf. sannanffi r were easily dispersed uniformly in. Gdparts, of 33% sodium hydroxide solution cooled to 0 C. This alkali-gum mixture was heated in a water bath, and a solid, rubber lil ze. mixture. resulted. 'I his.solid, rigid. yeerubber-lilre mass.-Was.cooled 4 and ground into fine particles. chloracetic acid were mixed in well with cooling. After the addition of the etherifying agent was complete, the resulting reaction mixture was heated in a water bath to C. and maintained at this temperature for a period of minutes. The mixture was, made acidic to phenolphthalein cooled and diluted with'300 parts of water. The reaction mixture'was dark in color and the re action product was precipitated by the addition 0i methanol removing nearly all of the dark color. The precipitated product was treated in a normal manner. This sodium carboxymethyl gum ether prepared from a sum yielding mannose on hydrolysis was readily dispersible in cold water to yield viscous 2 .A% sols of good clarity and stability. This product also showed the gel formatio 1 1 on the addition of a dilute ferrous sulfate solution. However, the tendency towards this gels formation was not as pronounced as in the cases of the derivatives from locust bean gum and'guargum.

The products of this general type find maul fol-duses. derivatives displaying good viscosity are excellent thickening agentsior printing pastes. The products Gr t-his invention find; numerous applications such as dressing and sizingagents, and uses in'em-ulsions, cosmetics, lotions, and the like. a

'While various modifications of the invention have been describedherein; in; detail; it will 'be ap parent that other variations are possible without departing from the; spirit of the invention. It is to be understood, therefore, that the details are illustrative-only and that the invention is to be limited only by the appended claims.

I'claimas my'i-nventiom I. A processofproducing; a carhoxyalkyl ether of a carbohydrate gum selected" fromthe group consistin-g of g-alactcmannans and glucomannans which comprises dispersing the; carbohydrate gumin a solution oran alkali; and then reacting the dispersed carbohydrate gum with an etherifying-agentselected from the group consisting of the halo lower'fatty acids'and salts thereof.

2*; A processor producing-a carboxyalkyl ether ofa carbohydrate gum selected from' the group, consisting of galactomannans and; glucomannans, which comprises dispersingthe carbohydrate gum at a; lowtemperatur'e in an aqueous solution oran allra-li, heating'the resultant mixture to an.

elevated temperature, and then reacting the mixturewith an etherifying agent selected from the group'consistiigig of the halolower fatty acidsand;

3-. A processof producing a carboxyalkyl ether of a carbohydrate gum selected from the group consisting of galactomannans;andglucomannans, which comprisesdispersing the carbohydrate gum in an aqueoussolutionofanalkall'at a temperaturemf approximately- 0-'Ci, raising the temperature of'theresultingnuxt-ure to a temperature: within the approximate range of Gil-90 C; for an. extended period Off time; cooling the reaction mixture-,- hreaking 'the reaction mixture up-intothe form of small; solid parti cles, mixing these solid p'articles-Witlhan e'therifying agentiselectedirom thegroup -consistingpf-the halo lower fatty acids and sal-ts thereof; heating the resultan-t mixtureto a'te'mperature withintheapproximate range or M -35 V for an extended period of time, thereafter cooling the reaction-mixture andydilutir-rg i't' with water' and' precipitating the reaction. DI'OdUOt, from: the water-by means of a water misciblerorg'anic solvent.

Then 22 parts of' 4. A process of producing a carboxyalkyl ether of a carbohydrate gum selected from the group consisting of galactomannans and glucomannans, which comprises dispersing the carbohydrate in the form of finely divided endosperm 5 particles derived from seeds containing such gums in an aqueous alkali at a low temperature, heating the mixture to a temperature within the approximate range of 6090' C. for an extended period of time, cooling the reaction mixture, breaking the reaction mixture up in the form of finely divided particles, reacting the finely divided particles with an alkali metal salt of chloracetic acid at an elevated temperature for an mixture with water, and precipitating the reac- 10 Number 6 v tion product from the water by or a water miscible organic solvent. .7

OW N- a. MOE.

- REFERENCES crrEn The following references are ofi record in the file of this-patent:

UNITED STATES mime-rs Name Date 1,350,820 Lilienfeld Aug. 24, 1920 1,504,178 Young Aug. 5, 1924 2,190,179 Ziese -et al Feb. 13, 1940 2,316,128- H Bock 'Apr. 6, 1943 2,344,179 Stahly Mar. 14, 1944 2,388,887 Weissberzer Nov. 13, 1945 

